The present invention relates to a carburetor automatic control system in an engine, and particularly to an improvement of a carburetor automatic control system in an engine. More specifically, it includes a temperature-sensitive operating device for operating a choke valve mounted in an intake passage of a carburetor so that the choke valve is opened in correspondence to increase in temperature of the engine, and a governor device for opening and closing a throttle valve mounted in the intake passage at a position downstream from the choke valve so as to maintain a preset rotational speed of the engine.